Vehicle power transmission device

ABSTRACT

A vehicle power transmission device includes: a first power transmission member including a cylindrical shaft end portion rotatably supported via a first bearing on an inner circumferential side of a non-rotating support wall; and a second power transmission member supported on the inside of the cylindrical shaft end portion via a second bearing radially overlapping with the first bearing by the cylindrical shaft end portion to be rotatable concentrically and relatively to the first power transmission member, the second power transmission member including a circular disc gear portion protruded to an outer circumferential side at a predetermined distance from the second bearing in a shaft center direction of the second power transmission member, at a portion facing the first bearing, the gear portion having an annular inner circumferential guide protruding portion for guiding to the first bearing a lubricant oil that passes through the second bearing for lubrication, that enters into a gap between the second bearing and the gear portion, and that travels to the outer circumferential side due to the centrifugal force.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2010-040535 filed onFeb. 25, 2010 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a technique for enhancing durability ofa bearing that rotatably supports a power transmission member includedin a vehicle power transmission device.

2. Description of the Related Art

A vehicle power transmission device is known that has a transmission, adifferential gear device, etc., for transmitting a drive force outputfrom a drive source such as an engine and an electric motor to axles.The device is described in Japanese Laid-Open Patent Publication No.2001-39179, for example. The transmission and the differential geardevice include a plurality of power transmission members such as gearsand rotation shafts each rotatably supported around a shaft center via abearing, etc., by a non-rotating case fixed to a vehicle body, forexample. The transmission and the differential gear device areconfigured to transmit the drive force sequentially through theplurality of the power transmission members.

SUMMARY OF THE INVENTION

In the vehicle power transmission device as described above, to shortenthe full length thereof for the purpose of enhancing vehiclemountability, etc., it is conceivable that shaft end portions of a pairof concentrically disposed power transmission members among theplurality of the power transmission members are arranged to radiallyoverlap with each other and that a pair of bearings rotatably supportingthe power transmission members are arranged to radially overlap witheach other. In other words, it is conceivable that the vehicle powertransmission device includes a first power transmission member having acylindrical shaft end portion rotatably supported via a first bearing onthe inner circumferential side of a non-rotating support wall and asecond power transmission member supported on the inside via a secondbearing radially overlapping with the first bearing by the cylindricalshaft end portion to be rotatable concentrically and relatively to thefirst power transmission member.

Although the second bearing is supplied with a sufficient amount oflubricant oil by supplying the lubricant oil from the innercircumferential side, since the lubricant oil passing through the secondbearing is blown off to the outer circumferential side by a centrifugalforce, it is difficult to supply a sufficient amount of the lubricantoil from the inner circumferential side to the first bearing arranged tooverlap with the outer circumferential side of the second bearing.Although it is conceivable to supply the lubricant oil to the firstbearing from the outer circumferential side for this reason, it isdifficult to supply a sufficient amount of the lubricant oil especiallywhen the first bearing rotates at a high speed because the lubricant oilis repelled even if supplied from the outer circumferential side.Therefore, the durability of the first bearing might deteriorate.

The present invention was conceived in view of the situations and it istherefore an object of the present invention to provide a vehicle powertransmission device capable of restraining the durability of the firstbearing from deteriorating due to insufficient lubrication even if thefirst bearing is arranged to radially overlap with the second bearing.

MEANS FOR SOLVING THE PROBLEMS

To achieve the above object, the first aspect of the present inventionprovides (a) a vehicle power transmission device comprising: a firstpower transmission member including a cylindrical shaft end portionrotatably supported via a first bearing on an inner circumferential sideof a non-rotating support wall; and a second power transmission membersupported on the inside of the cylindrical shaft end portion via asecond bearing radially overlapping with the first bearing by thecylindrical shaft end portion to be rotatable concentrically andrelatively to the first power transmission member, (b) the second powertransmission member including a circular disc gear portion protruded toan outer circumferential side at a predetermined distance from thesecond bearing in a shaft center direction of the second powertransmission member, (c) at a portion facing the first bearing, the gearportion having an annular inner circumferential guide protruding portionfor guiding to the first bearing a lubricant oil that passes through thesecond bearing for lubrication, that enters into a gap between thesecond bearing and the gear portion, and that travels to the outercircumferential side due to the centrifugal force.

The second aspect of the present invention provides the vehicle powertransmission device recited in the first aspect of the invention,wherein the inner circumferential guide protruding portion of the secondpower transmission member protrudes toward the first bearing at an innercircumferential side than an inner circumferential end portion of thesupport wall for fitting and attaching an outer ring of the firstbearing from the portion facing the first bearing in the gear portion tobe closer to the first bearing than one end surface of the innercircumferential end portion on a gear portion side.

The third aspect of the present invention provides the vehicle powertransmission device recited in the second aspect of the invention,wherein at one end portion of the inner circumferential end portion ofthe support wall toward the gear portion, an outer circumferential guideprotruding portion is formed that protrudes to the inner circumferentialside for guiding the lubricant oil to the first bearing.

The fourth aspect of the present invention provides the vehicle powertransmission device recited in any one of the first to third aspects ofthe invention, comprising (a) a speed reducer that reduces outputrotation of an electric motor disposed on the shaft center and adifferential gear device that distributes the output rotation of thespeed reducer to a pair of left and right axles, wherein (b) the firstpower transmission member is any one of a plurality of rotating elementsof the speed reducer, and wherein (c) the second power transmissionmember is an input shaft of the speed reducer disposed on an outputshaft of the electric motor in a relatively non-rotatable manner.

The fifth aspect of the present invention provides the vehicle powertransmission device recited in any one of the first to fourth aspects ofthe invention, wherein the gear portion is a parking lock gear.

The sixth aspect of the present invention provides the vehicle powertransmission device recited in any one of the first to fifth aspects ofthe invention, wherein the second power transmission member is rotatablysupported via the second bearing and a third bearing on the both sidesof the gear portion in the shaft center direction.

THE EFFECTS OF THE INVENTION

According to a vehicle power transmission device recited in the firstaspect of the invention, since the portion of a circular disc gearportion protruded to the second power transmission member facing thefirst bearing is provided with the annular inner circumferential guideprotruding portion for guiding to the first bearing the lubricant oilthat passes through the second bearing arranged to the innercircumferential side of the first bearing for lubrication, that entersinto the gap between the second bearing and the gear portion, and thattravels to the outer circumferential side due to the centrifugal force,the lubricant oil used for the lubrication of the second bearing issufficiently guided to the first bearing by the inner circumferentialguide protruding portion even if the first bearing rotates at a highspeed and, therefore, the durability of the first bearing can berestrained from deteriorating due to insufficient lubrication even ifthe first bearing is arranged to radially overlap with the secondbearing.

According to the vehicle power transmission device recited in the secondaspect of the invention, since the inner circumferential guideprotruding portion of the second power transmission member protrudestoward the first bearing at the inner circumferential side than theinner circumferential end portion of the support wall for fitting andattaching the outer ring of the first bearing from the facing portion inthe first bearing of the gear portion to be closer to the first bearingthan the one end surface of the inner circumferential end portion on agear portion side, the lubricant oil passing through the second bearingand traveling to the outer circumferential side due to the centrifugalforce is guided toward the first bearing by the inner circumferentialguide protruding portion without being discharged to the outercircumferential side from the gap between the inner circumferential endportion of the support wall and the gear portion and, therefore, thelubricant oil can be supplied to the first bearing in substantially thesame amount as the amount supplied to the second bearing.

According to the vehicle power transmission device recited in the thirdaspect of the invention, since at one end portion of the innercircumferential end portion of the support wall toward the gear portion,an outer circumferential guide protruding portion for guiding thelubricant oil to the first bearing is formed that protrudes to the innercircumferential side, the lubricant oil passing through the secondbearing and traveling to the outer circumferential side due to thecentrifugal force is prevented by the outer circumferential guideprotruding portion from moving toward the gap between the innercircumferential end portion of the support wall and the gear portion,the lubricant oil can be restrained from entering into the gap betweenthe inner circumferential end portion of the support wall and the gearportion to be discharged to the outer circumferential side without beingsupplied to the first bearing. Therefore, the lubricant oil can besupplied to the first bearing in substantially the same amount as theamount supplied to the second bearing.

According to the vehicle power transmission device recited in the fourthaspect of the invention, since a speed reducer that reduces outputrotation of an electric motor disposed on the shaft center and adifferential gear device that distributes the output rotation of thespeed reducer to a pair of left and right axles, wherein the first powertransmission member is any one of a plurality of rotating elements ofthe speed reducer, and wherein the second power transmission member isan input shaft of the speed reducer disposed on an output shaft of theelectric motor in a relatively non-rotatable manner, the lubricant oilis sufficiently supplied from the inner circumferential side to thefirst bearing disposed between the first power transmission devicemaking up the speed reducer coupled to the subsequent stage of theelectric motor that is relatively rotated at a high speed and thenon-rotating support wall, therefore, the durability of the firstbearing can be restrained from deteriorating due to insufficientlubrication even if the first bearing disposed between the two membersthat have a relatively large rotation difference is arranged to radiallyoverlap with the second bearing.

According to the vehicle power transmission device recited in the fifthaspect of the invention, since the gear portion is a parking lock gear,it can sufficiently supply the lubricant oil to the first bearing simplyby disposing the inner circumferential guide protruding portion at theparking lock gear that is the existing member without the need of newlydisposing a special oil passage for supplying the lubricant oil to thefirst bearing and, therefore, the cost can be reduced.

According to the vehicle power transmission device recited in the sixthaspect of the invention, since the second power transmission member isrotatably supported via the second bearing and a third bearing on theboth sides of the gear portion in the shaft center direction, thesupport stiffness of the second power transmission member cansufficiently be ensured.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 conceptually depicts a configuration of a drive-train of avehicle including a vehicle driving device according to one embodimentof the present invention.

FIG. 2 conceptually depicts a configuration of the drive-train viewedfrom the back of the vehicle depicted in FIG. 1.

FIG. 3 is a schematic for explaining a configuration of the vehicledriving device of FIG. 1.

FIG. 4 is a specific longitudinal section diagram of the configurationof the vehicle driving device of FIG. 1.

FIG. 5 is a partially enlarged cross-section diagram of the vehicledriving device of FIG. 4.

FIG. 6 is an enlarged cross-section diagram of a VI arrow view portionof FIG. 5.

FIG. 7 depicts a conventional differential case 102 having a firstcylindrical end portion not extended to the outer circumferential sideof the snap ring and is a diagram corresponding to FIG. 6 of theembodiment.

FIG. 8 is an enlarged diagram of a VIII arrow view portion of FIG. 5.

FIG. 9 is an enlarged cross-section diagram of the oil pump depicted inFIG. 5 along with peripheral members including the oil pump.

FIG. 10 depicts the pump body, the pump cover, the drive gear, thedriven gear, and the pump shaft assembled to each other in advancebefore the fixation to the bottomed cylindrical case, i.e., an oil pumpsub-assembly viewed from the direction corresponding to an X arrow viewdirection of FIG. 9.

FIG. 11 is a cross-section diagram of a cross-section of the IX-IX arrowview portion of FIG. 10.

FIG. 12 depicts how the oil pump sub-assembly of FIG. 11 is assembled tothe bottomed cylindrical case.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Exemplary embodiments of the present invention will now be described indetail with reference to the drawings. In the following embodiments, thefigures are simplified or modified as needed and the dimension ratiosand shapes of portions or the like are not necessarily accuratelydepicted.

First Embodiment

FIG. 1 conceptually depicts a configuration of a drive-train of avehicle 12 including a vehicle driving device 10 according to oneembodiment of the present invention. FIG. 2 conceptually depicts aconfiguration of the drive-train viewed from the back of the vehicle 12.In FIGS. 1 and 2, the vehicle 12 includes pairs of left and right frontwheels 14 and rear wheels 16 respectively disposed on the front side andthe rear side, and the vehicle driving device 10 fixed via a mountmember 20 to a vehicle body 18 as depicted in FIG. 2 on the front sideof the vehicle 12 to rotationally drive the pair of the front wheels 14via a pair of left and right drive shafts (axles) 22.

The vehicle driving device 10 includes a driving portion 26 having anelectric motor 24 functioning as a drive source of the vehicle 12 andtransversally mounted on the vehicle 12, and a transaxle portion 28functioning as a power transmission device that reduces and distributesthe output rotation of the driving portion 26 to a pair of left andright drive shafts 22. The electric motor 24 is activated by a drivecurrent supplied from an inverter 30 disposed on the vehicle body 18,for example. The vehicle 12 is an FF (front-motor front-drive) typeelectric vehicle that has the front wheels 14 rotationally driven asdrive wheels by the electric motor 24 disposed on the front side.

FIG. 3 is a schematic for explaining a configuration of the vehicledriving device 10 of FIG. 1. FIG. 4 is a specific longitudinal sectiondiagram of the configuration of the vehicle driving device 10. In FIGS.3 and 4, the vehicle driving device 10 includes the electric motor 24, aspeed reducer 34, and a differential gear device 36 housed in athree-divided transaxle case 32 and disposed on a common shaft centerC1. The driving portion 26 mainly includes the electric motor 24 and thetransaxle portion 28 mainly includes the speed reducer 34 and thedifferential gear device 36.

The transaxle case 32 consists of a cylindrical case 38 mainly housingthe electric motor 24, a bottomed cylindrical case 44 mainly housing thespeed reducer 34 and the differential gear device 36 and having anopening surface 40 combined with one opening surface 42 of thecylindrical case 38 and fastened to each other by a bolt not shown, forexample, and a circular disc case cover 48 combined with the otheropening surface 46 of the cylindrical case 38 and fastened to each otherby a bolt not shown, for example. The end portion of the cylindricalcase 38 on the side of the bottomed cylindrical case 44 has an annulardisc partition wall 50 formed and integrally protruding inward from theinner circumference surface. An oil pan 52 is fixed to an openingportion formed on a lower side surface of the cylindrical case 38 suchthat the opening is closed. This oil pan 52 acts as an oil receiver thatreceives lubricant oil when the lubricant oil circulating within thetransaxle case 32 recirculates to the lower portion of the cylindricalcase 38. An annular disc support wall 54 is fixed to the opening surface40 of the bottomed cylindrical case 44 by a bolt 56, for example. Thecylindrical case 38, the bottomed cylindrical case 44, the case cover48, and the support wall 54 are made of die-cast aluminum alloy, forexample.

The electric motor 24 includes a stator 58 integrally fixed to thecylindrical case 38 by, for example, a bolt not shown, a rotor 60disposed on the inner circumferential side of the stator 58, and acylindrical output shaft 64 that is disposed on the outercircumferential side of one of the drive shafts 22 disposed on the rightof the vehicle 12 depicted in FIG. 1 for the fixation of the rotor 60and that is rotatably supported at the both end portions by a motor sidebearing 62 fit and attached to the partition wall 50 of the cylindricalcase 38 and a bearing 63 disposed, for example, on the case cover 48.The output shaft 64 is rotationally driven in accordance with a drivecurrent supplied from the inverter 30 to the stator 58. The electricmotor 24 configured as described above is coupled to and rotationallydrives an input shaft 66 of the speed reducer 34 coupled to thesubsequent stage thereof.

FIG. 5 is a partially enlarged cross-section diagram of the vehicledriving device 10 of FIG. 4. As depicted in FIGS. 3 and 5, the speedreducer 34 is a planetary gear type speed reducer that includes acylindrical input shaft (second power transmission member) 66 disposedon the outer circumferential side of the one drive shaft 22 and coupledto the output shaft 64 of the electric motor 24 in a relativelynon-rotatable manner, for example, by the spline fitting, a sun gear S1fit with a shaft end portion 68 of the input shaft 66 on the sidefurther from the electric motor 24, i.e., on the side closer to thedifferential gear device 36 in a relatively non-rotatable manner, forexample, by the spline fitting, a stepped pinion P1 having a smalldiameter portion 70 and a large diameter portion 72 with the largediameter portion 72 engaged with the sun gear S1, a carrier (first powertransmission member) CA1 supporting the stepped pinion P1 via a pinionshaft 74 so as to be rotatable and revolvable about the sun gear S1; anda ring gear R1 fixed to the bottomed cylindrical case 44 concentricallyto the sun gear S1 in a relatively non-rotatable manner and engaged withthe small diameter portion 70 of the stepped pinion P1. The carrier CA1corresponds to any one of a plurality of rotating elements making up thespeed reducer.

The carrier CA1 has a cylindrical shaft end portion 78 rotatablysupported around the shaft center C1 via a first bearing 76 on the innercircumferential side of the non-rotating support wall 54. The carrierCA1 is coupled to a differential case 80 of the differential gear device36 disposed on the subsequent stage of the speed reducer 34 and acts asan output member of the speed reducer 34. The speed reducer 34configured as described above reduces the rotation input from theelectric motor 24 to the input shaft 66 to output the rotation to thedifferential gear device 36.

The input shaft 66 is supported by the shaft end portion 78 on theinside via a second bearing 82 radially overlapping with the firstbearing 76 and is disposed concentrically to the carrier CA1 in arelatively rotatable manner. The input shaft 66 includes a circular discparking lock gear (gear portion) 84 protruding outward at apredetermined distance from the second bearing 82 in the shaft center C1direction. The input shaft 66 is rotatably supported via a third bearing86 by the partition wall 50 on the side of the parking lock gear 84closer to the electric motor 24 and is rotatably supported via thesecond bearing 82 and the third bearing 86 on the both sides of theparking lock gear 84 in the shaft center C1 direction.

FIG. 6 is an enlarged cross-section diagram of a VI arrow view portionof FIG. 5. As depicted in FIG. 6, the sun gear S1 is prevented fromrelatively moving toward the differential gear device 36 by an annularsnap ring 90 fit and attached into an annular snap ring groove 88 formedin the outer circumferential surface of the shaft end portion 68 of theinput shaft 66 on the side of the sun gear S1 closer to the differentialgear device 36. Although the sun gear 51 of this embodiment consists ofa helical gear and is affected by a thrust force causing a relativemovement toward the differential gear device 36, for example, when theelectric motor 24 outputs the drive force to drive the vehicle 12 inreverse or when the electric motor 24 is subjected to the regenerativecontrol or the like, the relative movement toward the differential geardevice 36 is prevented by the snap ring 90 even in such a case.

As depicted in FIG. 5, the differential gear device 36 includes thetwo-divided differential case 80, a pair of side gears 92 opposite toeach other on the shaft center C1 in the differential case 80, and threepinions 94 disposed at regular intervals in the circumferentialdirection between the side gears 92 to be engaged with each of a pair ofthe side gears 92, and is disposed adjacently to the side of the inputshaft 66 further from the electric motor 24 in the shaft center C1direction.

The differential case 80 consists of a first cylindrical differentialcase 96 disposed on the side closer to the electric motor 24 in theshaft center C1 direction and a second cylindrical differential case 98disposed on the side of the first differential case 96 further from theelectric motor 24 and combined with the first differential case 96 to befastened to each other by a bolt not shown, for example, and isrotatably disposed around the shaft center C1.

As depicted in FIG. 6, the first differential case 96 includes a firstcylindrical end portion (cylindrical end portion) 100 extended towardthe shaft end portion 68 of the input shaft 66 and to the outercircumferential side of the snap ring 90 fit and attached to the shaftend portion 68. The first cylindrical end portion 100 is formed suchthat a radial distance t1 of an annular gap formed between the firstcylindrical end portion 100 and the snap ring 90 is set smaller than apredetermined value, i.e., a groove depth t2 of the snap ring groove 88.The snap ring 90 is affected by a centrifugal force to the outercircumferential side when the input shaft 66 is rotated and is affectedby the thrust force toward the differential gear device 36 when the sungear S1 is biased toward the differential gear device 36 by the thrustforce at the time of output of the reverse drive force from the electricmotor 24 or at the time of the regenerative control of the electricmotor 24, for example. Therefore, although the snap ring 90 may bedeformed to the outer circumferential side or toward the differentialgear device 36, the slip-off thereof is prevented since the snap ring 90abuts on the inner circumferential surface the first cylindrical endportion 100 before completely slipping off from the snap ring groove 88.

FIG. 7 depicts a conventional differential case 102 having a firstcylindrical end portion 101 not extended to the outer circumferentialside of the snap ring 90. As depicted in FIG. 7, the differential case102 has a radial distance t3 of an annular gap formed between the firstcylindrical end portion 101 and the snap ring 90 set larger than thegroove depth t2 of the snap ring groove 88. Therefore, if the snap ring90 is deformed to the outer circumferential side and toward thedifferential gear device 36, the snap ring 90 may slip off from the snapring groove 88.

Referring to FIG. 6 again, in an annular gap formed between the outercircumferential surface of the shaft end portion 68 of the input shaft66 in the axial direction of C1 and the inner circumferential surface ofthe first cylindrical end portion 100, an oil seal 103 is disposed thatseals the gap in an oil tight manner. The oil seal 103 of thisembodiment is configured with a relatively simple structure because ofthe narrower (smaller) radial distance of the gap and includes anannular cored bar 104 made of metal, for example, fit and attached tothe inner circumferential surface of the first cylindrical end portion100 and a sealing member (lip) 106 made of synthetic resin, for example,fixed to the inner circumferential side of the cored bar 104. The radialdistance t1 is set such that the snap ring 90 abuts on the firstcylindrical end portion 100 so as not to exceed a predeterminedallowable deformation range in the radial direction of the oil seal 103even if the input shaft 66 and the first differential case 96 arerelatively moved in the radial direction. The allowable deformationrange is a radial deformation range of the oil seal 103 causing noleakage of lubricant oil from the oil seal 103 even if the oil seal 103is deformed in accordance with the radial relative movement of the inputshaft 66 and the first differential case 96 and is empirically obtainedin advance. Therefore, if the input shaft 66 and the first differentialcase 96 are relatively moved in the radial direction, the snap ring 90abuts on the first cylindrical end portion 100 when the deformation ofthe oil seal 103 is within the allowable deformation range.

Although the annular gap formed between the outer circumferentialsurface of the shaft end portion 68 and the inner circumferentialsurface of the first cylindrical end portion 100 described above is incommunication with a differential case internal space A1 making up adelivery oil passage 126 described later to be supplied with thelubricant oil, the first cylindrical end portion 100 is provided with agap reducing portion 108 that reduces the volume of the annular gap todecrease an amount of the lubricant oil retained in the gap. Therefore,when the first differential case 96 rotates while the annular gapretains the lubricant oil, a bias force applied to the oil seal 103 fromthe retained lubricant oil toward the side opposite to the gap issmaller as compared to the case of absence of the gap reducing portion108.

Referring to FIGS. 3 and 5, the first differential case 96 is disposedintegrally with the carrier CA1 and is rotatably supported around theshaft center C1 via the carrier CA1 and the first bearing 76. To thefirst differential case 96, the output rotation of the speed reducer 34is input through the carrier CA1. The first differential case 96 alsoacts as an input member of the differential gear device 36. The firstdifferential case 96 has outer circumferential teeth 110circumferentially continuously formed for rotationally driving a pinion156 of an oil pump 120 described later.

The second differential case 98 is rotatably supported around the shaftcenter C1 via a differential side bearing 114 on the innercircumferential side of an annular disc bottom wall 112 of the bottomedcylindrical case 44. The second differential case 98 includes a secondcylindrical end portion 116 protruding to the side opposite to the firstdifferential case 96 and provided with an annular groove 136 and asecond delivery oil passage 138 making up a portion of a lubricant oilsupplying device 118 described later.

The side gear 92 of the pair of the side gears 92 closer to the electricmotor 24 is coupled on the inner circumferential side to the shaft endportion of the one drive shaft 22 in a relatively non-rotatable mannerby the spline fitting, for example. The side gear 92 of the pair of theside gears 92 further from the electric motor 24 is coupled on the innercircumferential side to the shaft end portion of the other drive shaft22 in a relatively non-rotatable manner by the spline fitting, forexample. The one drive shaft 22 is rotatably supported around the shaftcenter C1 by the inner circumferential surface of the input shaft 66,for example, and the other drive shaft 22 is rotatably supported aroundthe shaft center C1 by the inner circumferential surface of the secondcylindrical end portion 116 of the second differential case 98.

The differential gear device 36 configured as described above isrotationally driven by the speed reducer 34 to transmit a drive force toa pair of the drive shafts 22 disposed on the shaft center C1 whileallowing a rotational difference between the drive shafts 22.

As depicted in FIG. 3, the vehicle driving device 10 includes thelubricant oil supplying device 118 for supplying lubricant oil to, forexample, lubrication sites such as a gear engagement site and a sitebetween two relatively rotating members of the electric motor 24, thespeed reducer 34, and the differential gear device 36 configured asabove. The lubricant oil supplying device 118 includes the internal geartype oil pump 120 fixed to the inside bottom surface of the bottom wall112 of the bottomed cylindrical case 44, a suction oil passage 124 forguiding the lubricant oil accumulated in the oil pan 52 through astrainer 122 to the oil pump 120, and the delivery oil passage 126branched into a plurality of parts on the way for guiding the lubricantoil sucked through the suction oil passage 124 and pressurized by theoil pump 120 to the lubrication sites.

As depicted in FIG. 5, the suction oil passage 124 is made up of a firstsuction oil passage 128 that is in communication through the strainer122 with a lubricant oil accumulation space A2 formed by the openingportion in the lower side surface of the cylindrical case 38 and the oilpan 52 and that opens in the one opening surface 42 of the cylindricalcase 38 and a second suction oil passage 134 that opens in the openingsurface 40 of the bottomed cylindrical case 44 oppositely to the firstsuction oil passage 128 to be in communication with the first suctionoil passage 128 and that opens in a bottom surface of a fitting recessportion 130 formed inside the bottom wall 112 of the bottomedcylindrical case 44 to be in communication with a pump chamber 132 ofthe oil pump 120. As indicated by a broken line arrow B of FIG. 5, thesuction oil passage 124 supplies the lubricant oil from the lubricantoil accumulation space A2 via the strainer 122, the first suction oilpassage 128, and the second suction oil passage 134 to the oil pump 120.

The delivery oil passage 126 includes a first delivery oil passage notshown that opens in the bottom surface of the fitting recess portion 130to be in communication with the pump chamber 132 of the oil pump 120 andthat is in communication with the annular groove 136 formed in the outercircumferential surface of the second cylindrical end portion 116 of thesecond differential case 98, the annular groove 136, the second deliveryoil passage 138 formed in the second cylindrical end portion 116 forallowing communication between the annular groove 136 and thedifferential case internal space A1, the differential case internalspace A1, and a cylindrical space A3 formed between the input shaft 66and the one drive shaft 22 to be in communication with the differentialcase internal space A1.

FIG. 8 is an enlarged diagram of a VIII arrow view portion of FIG. 5. Asdepicted in FIG. 8, the delivery oil passage 126 also includes aplurality of oil holes 140 (only one is depicted in FIG. 8) that aredisposed in the input shaft 66, for example, at circumferentiallyregular intervals in a radially penetrating manner to be incommunication with the cylindrical space A3 and that is in communicationwith a first annular space A4 formed between the inner circumferentialsurface of the sun gear S1 and the outer circumferential surface of theinput shaft 66, the first annular space A4, a plurality of oil grooves142 (only one is depicted in FIG. 8) that is in communication with thefirst annular space A4 and that is formed in an end surface of the sungear S1 abutting on an inner ring of the second bearing 82, for example,at circumferentially regular intervals in a radially penetrating mannerto be capable of supplying the lubricant oil to the second bearing 82,and a second annular space A5 formed between the first bearing 76, thecylindrical shaft end portion 78, and the second bearing 82 and theparking lock gear 84 in the shaft center C1 direction to be capable ofdischarging the lubricant oil from the second bearing 82 and supplyingthe lubricant oil to the first bearing 76.

As indicated by a broken line arrow D of FIG. 5, the delivery oilpassage 126 supplies the lubricant oil from the pump chamber 132 of theoil pump 120 via the first delivery oil passage, the annular groove 136,the second delivery oil passage 138, and the differential case internalspace A1 to the cylindrical space A3. As indicated by the broken linearrow D of FIG. 5 and a broken line arrow D1 of FIG. 8, the lubricantoil is supplied from the cylindrical space A3 via the oil holes 140, thefirst annular space A4, and the oil grooves 142 to the second bearing82. As indicated by the broken line arrow D of FIG. 5 and broken linearrows D2 to D3 of FIG. 8, the lubricant oil is supplied from the secondbearing 82 via the second annular space A5 to the first bearing 76. Thelubricant oil supplied to the first bearing 76 is discharged to theouter circumferential side as indicated by the broken line arrow D ofFIG. 5 and a broken line arrow D4 of FIG. 8.

As depicted in FIG. 8, an opposite portion in one surface of the parkinglock gear 84 toward the first bearing 76 is provided with an annularinner circumferential guide protruding portion 146 that integrallyprotrudes at the inner circumferential side than an innercircumferential end portion 144 of the support wall 54 for fitting andattaching an outer ring of the first bearing 76 from the oppositeportion in one surface of the parking lock gear 84 toward the firstbearing 76 to be closer to the first bearing 76 than the end surface ofthe inner circumferential end portion 144 toward the parking lock gear84. The inner circumferential guide protruding portion 146 includes afirst tapered inner circumferential surface 148 having the innerdiameter continuously increasing toward the first bearing 76. The innercircumferential guide protruding portion 146 is designed to guide thelubricant oil that passes through the second bearing 82 for lubrication,that enters into the second annular space A5, and that travels to theouter circumferential side due to the centrifugal force, along the firsttapered inner circumferential surface 148 toward the first bearing 76 asindicated by the broken line arrow D2 of FIG. 8.

At the end portion of the inner circumferential end portion 144 towardthe parking lock gear 84, an annular outer circumferential guideprotruding portion 150 is disposed that integrally protrudes to theinner circumferential side while integrally protruding closer to theparking lock gear 84 than the end surface of the inner circumferentialguide protruding portion 146 toward the first bearing 76. The outercircumferential guide protruding portion 150 and the innercircumferential guide protruding portion 146 are arranged on the outercircumferential side and the inner circumferential side to overlap witheach other in the traveling direction of the lubricant oil that goes tothe outer circumferential side due to the centrifugal force, i.e., theradial direction. The outer circumferential guide protruding portion 150includes a second tapered inner circumferential surface 152 having theinner diameter continuously increasing toward the first bearing 76. Theouter circumferential guide protruding portion 150 is designed to guidethe lubricant oil that travels to the outer circumferential side due tothe centrifugal force after being guided toward the first bearing 76 bythe inner circumferential guide protruding portion 146, along the secondtapered inner circumferential surface 152 toward the first bearing 76 asindicated by the broken line arrow D3 of FIG. 8. The outercircumferential guide protruding portion 150 also has a functional rolein preventing the lubricant oil that travels to the outercircumferential side due to the centrifugal force after being guidedtoward the first bearing 76 by the inner circumferential guideprotruding portion 146 from going between the parking lock gear 84 andthe inner circumferential end portion 144.

To the first bearing that rotatably supports the carrier CA1 making upthe speed reducer 34 coupled to the subsequent stage of the electricmotor 24 rotated at a higher speed as compared to, for example, anengine, the lubricant oil is sufficiently guided from the innercircumferential side by the inner circumferential guide protrudingportion 146 and the outer circumferential guide protruding portion 150.

Referring to FIG. 5 again, the delivery oil passage 126 is provided withoil passages for supplying the lubricant oil to the electric motor 24and oil passages for supplying the lubricant oil to the gear engagementsites of the rotating elements of the speed reducer 34, for example,along with those described above.

FIG. 9 is an enlarged cross-section diagram of the oil pump 120 depictedin FIG. 5 along with peripheral members including the oil pump 120. Asdepicted in FIG. 9, the oil pump 120 includes a short cylindrical pumpbody 154 having the pump chamber 132 that is recessed oppositely to thebottom surface of the fitting recess portion 130 of the bottomedcylindrical case 44 to be connected to the second suction oil passage(suction oil passage) 134 opening in the bottom surface and the firstdelivery oil passage; a pump shaft 158 that is provided to penetrate thepump body 154 while being rotatably supported by the pump body 154 andthat has one end portion fit in a relatively non-rotatable manner withthe pinion 156 engaging with outer circumferential teeth 110 disposed inthe first differential case 96; an external gear type drive gear (rotor)160 that is provided concentrically to the pump shaft 158 while beingfit in a relatively non-rotatable manner with the other end portion ofthe pump shaft 158 and that is rotationally driven around a shaft centerC2 in parallel with the shaft center C1 along with the pump shaft 158when the pump shaft 158 is rotationally driven by the first differentialcase 96 via the outer circumferential teeth 110 and the pinion 156; aninternal gear type driven gear (rotor) 162 that is engaged with thedrive gear 160 and that is fit into the pump chamber 132 so as to berotatable around a shaft center C3 eccentric to the shaft center C2; anda pump cover 164 that is disposed between the pump body 154 and thebottom wall 112 of the bottomed cylindrical case 44 in the fittingrecess portion 130 and that is fixed to the pump body 154 to make thedrive gear 160 and the driven gear 162 unable to be pulled out from thepump chamber 132. The pump body 154 and the pump cover 164 are made ofdie-cast aluminum alloy, for example, and the drive gear 160 and thedriven gear 162 are molded by sintering (powder metallurgy), forexample. Although the pump cover 164 has a communication hole 165 thatallows communication between the pump chamber 132 of the pump body 154and each of the second suction oil passage 134 and the first deliveryoil passage opening in the bottom surface of the fitting recess portion130, the pump cover 164 accurately connects the pump chamber 132 and thesecond suction oil passage 134 and the first delivery oil passagebecause of being made by die-casting as described above.

FIG. 10 depicts the pump body 154, the pump cover 164, the drive gear160, the driven gear 162, and the pump shaft 158 assembled to each otherin advance before the fixation to the bottomed cylindrical case 44,i.e., an oil pump sub-assembly 166 viewed from the directioncorresponding to an X arrow view direction of FIG. 9. The oil pump 120depicted in FIG. 5 is depicted as a V-V arrow view portion cross-sectionof FIG. 10 and the oil pump 120 depicted in FIG. 9 is depicted as aIX-IX arrow view portion cross-section of FIG. 10. FIG. 11 is across-section diagram of a cross-section of the XI-XI arrow view portionof FIG. 10. As depicted in FIG. 10 or FIG. 11, the pump body 154 and thepump cover 164 are relatively positioned to some extent in the directionorthogonal to the shaft center C2 by a pair of positioning pins 176having one end portions pressed into a pair of pin press fit holes 170disposed in a first combination surface 168 of the pump cover 164 forthe pump body 154 and other end portions loosely fit into a pair ofpositioning pin holes 174 disposed oppositely to the pair of the pinpress fit holes 170 in a second combination surface 172 of the pump body154 for the pump cover 164 in a state of fitting leaving a gap. Thepositioning pins 176 position the pump body 154 and the pump cover 164in a state permitting a relative movement by the gap between thepositioning pins 176 and the positioning pin holes 174. In the pumpcover 164, a spot facing hole 178 is formed oppositely to the bottomsurface of the fitting recess portion 130, and the pump body 154 and thepump cover 164 are fastened to each other by a hexagonal hole head bolt(headed bolt) 182 that has a head with a length in the shaft centerdirection shorter than the spot facing depth of the spot facing hole 178to be inserted into the spot facing hole 178 such that the head ishidden in the spot facing hole 178 and that is threaded into a femalescrew 180 formed in the pump body 154. Even if loosened, the hexagonalhole head bolt 182 is not drop off since the bolt hits against thebottom wall 112 of the bottomed cylindrical case 44.

Referring to FIG. 9 again, the pump body 154 is fit into the fittingrecess portion 130 having a cylindrical inner circumferential surface184 formed in the bottom surface of the bottomed cylindrical case 44 tobe positioned in the direction orthogonal to the shaft center C2relatively to the bottomed cylindrical case 44. As a result, the pumpshaft 158 rotatably supported by the pump body 154 and the differentialcase 80 rotatably supported via the differential side bearing 114 by thebottomed cylindrical case 44 are positioned to each other in thedirection orthogonal to the shaft center C1.

An outer circumferential surface 186 of the pump cover 164 is set to belocated at the inner circumferential side than a cylindrical outercircumferential surface 188 of the pump body 154 regardless of an amountof movement of the pump cover 164 relative to the pump body 154 inaccordance with the gap between the positioning pins 176 and thepositioning pin holes 174. As a result, a predetermined annular gap isformed between the outer circumferential surface 186 of the pump cover164 and the cylindrical inner circumferential surface 184 of the fittingrecess portion 130. Therefore, the pump body 154 is fit into the fittingrecess portion 130 such that the cylindrical outer circumferentialsurface 188 can engage with the cylindrical inner circumferentialsurface 184 of the fitting recess portion 130 at any circumferentialposition.

FIG. 12 depicts how the oil pump sub-assembly 166 is assembled to thebottomed cylindrical case 44. As depicted in FIG. 12, the oil pumpsub-assembly 166 is fit into the fitting recess portion 130 of thebottomed cylindrical case 44 disposed with the opening facing upward inconsideration of assembly property as indicated by an arrow E of FIG.12. Since the pump cover 164 is fastened to the pump body 154 by thebolt 182, the driven gear 162 and the drive gear 160 are prevented fromdropping off from the pump chamber 132 by the pump cover 164. The oilpump sub-assembly 166 is fixed to the bottomed cylindrical case 44 byinserting hexagonal hole head bolts 190 into a plurality ofthrough-holes 192 circumferentially arranged and penetrating the pumpbody 154 and the pump cover 164 in the thickness direction and byscrewing the bolts into a plurality of female screws 194 respectively,formed in the bottom surface of the fitting recess portion 130oppositely to the through-holes 192. The oil pump 120 is attached to thebottomed cylindrical case 44 as the oil pump sub-assembly 166 formed byassembling the pump body 154, the drive gear 160, the driven gear 162,the pump shaft 158, and the pump cover 164 to each other in advance.

The pinion 156 is fit into the pump shaft 158, and the differential geardevice 36 and the speed reducer 34 are assembled to the bottomedcylindrical case 44 in predetermined order. As depicted in FIG. 5, inthe state after the members including the oil pump 120 and the ring gearR1 are assembled, the pinion 156 is prevented from slipping off from thepump shaft 158 by the ring gear R1 adjacently disposed in the shaftcenter C2 direction. The ring gear R1 is a member making up a speedreducer disposed within a transaxle case.

As described above, according to the transaxle portion 28 acting as thepower transmission device of this embodiment, since the portion of theparking lock gear (gear portion) 84 opposite to the first bearing 76 isprovided with the annular inner circumferential guide protruding portion146 for guiding to the first bearing 76 the lubricant oil that passesthrough the second bearing 82 for lubrication, that enters into the gapbetween the second bearing 82 and the parking lock gear 84, and thattravels to the outer circumferential side due to the centrifugal force,the lubricant oil used for the lubrication of the second bearing 82 issufficiently guided to the first bearing 76 by the inner circumferentialguide protruding portion 146 even if the first bearing 76 rotates at ahigh speed and, therefore, the durability of the first bearing can berestrained from deteriorating due to insufficient lubrication even ifthe first bearing 76 is arranged to radially overlap with the secondbearing 82.

According to the transaxle portion 28 of the present invention, sincethe inner circumferential guide protruding portion 146 integrallyprotrudes at the inner circumferential side than the innercircumferential end portion 144 of the support wall 54 for fitting andattaching the outer ring of the first bearing 76 from the oppositeportion in one surface of the parking lock gear 84 toward the firstbearing 76 to be closer to the first bearing 76 than the end surface ofthe inner circumferential end portion 144 toward the parking lock gear84, the lubricant oil passing through the second bearing 82 andtraveling to the outer circumferential side due to the centrifugal forceis guided toward the first bearing 76 by the inner circumferential guideprotruding portion 146 without being discharged to the outercircumferential side from the gap between the inner circumferential endportion 144 of the support wall 54 and the parking lock gear 84 and,therefore, the lubricant oil can be supplied to the first bearing 76 insubstantially the same amount as the amount supplied to the secondbearing 82.

According to the transaxle portion 28 of the present invention, since atone end portion of the inner circumferential end portion 144 of thesupport wall 54 toward the parking lock gear 84, an annular outercircumferential guide protruding portion 150 is formed that integrallyprotrudes to the inner circumferential side while integrally protrudingcloser to the parking lock gear 84 than the end surface of the innercircumferential guide protruding portion 146 toward the first bearing76, the lubricant oil passing through the second bearing 82 andtraveling to the outer circumferential side due to the centrifugal forceis prevented by the outer circumferential guide protruding portion 150from moving toward the gap between the inner circumferential end portion144 of the support wall 54 and the parking lock gear 84, the lubricantoil can be restrained from entering into the gap between the innercircumferential end portion 144 of the support wall 54 and the parkinglock gear 84 to be discharged to the outer circumferential side withoutbeing supplied to the first bearing 76. Therefore, the lubricant oil canbe supplied to the first bearing 76 in substantially the same amount asthe amount supplied to the second bearing 82.

According to the transaxle portion 28 of the present invention, sincethe first bearing 76 is disposed between the carrier CA1 that is one ofthe rotating elements of the speed reducer 34 for reducing the outputrotation of the electric motor 24 and the non-rotating support wall 54,the lubricant oil is sufficiently supplied from the innercircumferential side to the first bearing 76 disposed between thecarrier CA1 and the support wall 54 that have a relatively largerelative rotation difference and, therefore, the durability of the firstbearing 76 can be restrained from deteriorating due to insufficientlubrication even if the first bearing 76 is arranged to radially overlapwith the second bearing 82.

According to the transaxle portion 28 of the present invention, sincethe inner circumferential guide protruding portion 146 is integrallydisposed at the opposite portion in one surface of the parking lock gear84 toward the first bearing 76, the lubricity of the first bearing 76can be enhanced simply by changing the shape of the existing member (theparking lock gear 84) without the need of newly disposing a special oilpassage for supplying the lubricant oil to the first bearing 76 and,therefore, the cost can be reduced.

According to the transaxle portion 28 of the present invention, sincethe input shaft 66 is rotatably supported via the second bearing 82 andthe third bearing 86 on the both sides of the parking lock gear 84 inthe shaft center C1 direction, the support stiffness of the input shaft66 can sufficiently be ensured.

Although the embodiments of the present invention have been described indetail with reference to the drawings, the present invention is notlimited to the embodiments and may be implemented in other forms.

For example, although the first bearing 76 is disposed between thesupport wall 54 and the shaft end portion 78 of the carrier CA1 of thespeed reducer 34 for the rotatable support thereof and the secondbearing 82 is disposed between the shaft end portion 78 of the carrierCA1 and the input shaft 66 for the rotatable support thereof in theembodiments, this is not a limitation and the bearings may be disposedbetween other two members for the support thereof. The present inventionis basically applicable as long as the first bearing 76 and the secondbearing 82 are disposed to overlap in the radial direction.

Although the inner circumferential guide protruding portion 146 isintegrally disposed on the parking lock gear 84 in the embodiments, theinner circumferential guide protruding portion 146 may be separatelyformed and fixedly disposed on the parking lock gear 84 or may bedisposed on a member located at a predetermined distance from the firstbearing 76 other than the parking lock gear 84, for example.

Although the inner circumferential surface of the inner circumferentialguide protruding portion 146 is formed in a tapered shape in theembodiment, the inner circumferential surface may be formed in acylindrical shape or a curved shape, for example.

The outer circumferential guide protruding portion 150 disposed on theinner circumferential end portion 144 of the support wall 54 in theembodiments may not necessarily be disposed.

Although the vehicle driving device 10 includes the electric motor 24,the speed reducer 34 and the differential gear device 36 in theembodiments, the electric motor 24 and the speed reducer 34 are notnecessarily be included. For example, instead of the electric motor 24,output of an engine may be input to the speed reducer 34. The output ofthe electric motor 24 may directly be output to the differential geardevice 36 without including the speed reducer 34. The differential geardevice 36 may be included.

Although the vehicle 12 of the embodiments is of the FF type, thevehicle may be of the FR (front-motor rear-drive) type, for example, ora vehicle employing another drive type.

The pump cover 164 of the oil pump 120 of the embodiments may notnecessarily be included.

The first cylindrical end portion 100 of the first differential case 96in the embodiments may not necessarily be extended to the outercircumferential side of the snap ring 90.

It is to be understood that the above are merely exemplary embodimentsand that the present invention may be implemented in variously modifiedor altered forms based on the knowledge of those skilled in the artwithout departing from the spirit thereof although not exemplaryillustrated one by one.

1. A vehicle power transmission device comprising: a first powertransmission member including a cylindrical shaft end portion rotatablysupported via a first bearing on an inner circumferential side of anon-rotating support wall; and a second power transmission membersupported on the inside of the cylindrical shaft end portion via asecond bearing radially overlapping with the first bearing by thecylindrical shaft end portion to be rotatable concentrically andrelatively to the first power transmission member, the second powertransmission member including a circular disc gear portion protruded toan outer circumferential side at a predetermined distance from thesecond bearing in a shaft center direction of the second powertransmission member, at a portion facing the first bearing, the gearportion having an annular inner circumferential guide protruding portionfor guiding to the first bearing a lubricant oil that passes through thesecond bearing for lubrication, that enters into a gap between thesecond bearing and the gear portion, and that travels to the outercircumferential side due to the centrifugal force.
 2. The vehicle powertransmission device of claim 1, wherein the inner circumferential guideprotruding portion of the second power transmission member protrudestoward the first bearing at an inner circumferential side than an innercircumferential end portion of the support wall for fitting andattaching an outer ring of the first bearing from the portion facing thefirst bearing in the gear portion to be closer to the first bearing thanone end surface of the inner circumferential end portion on a gearportion side.
 3. The vehicle power transmission device of claim 2,wherein at one end portion of the inner circumferential end portion ofthe support wall toward the gear portion, an outer circumferential guideprotruding portion is formed that protrudes to the inner circumferentialside for guiding the lubricant oil to the first bearing.
 4. The vehiclepower transmission device of claim 1, comprising a speed reducer thatreduces output rotation of an electric motor disposed on the shaftcenter and a differential gear device that distributes the outputrotation of the speed reducer to a pair of left and right axles, whereinthe first power transmission member is any one of a plurality ofrotating elements of the speed reducer, and wherein the second powertransmission member is an input shaft of the speed reducer disposed onan output shaft of the electric motor in a relatively non-rotatablemanner.
 5. The vehicle power transmission device of claim 2, comprisinga speed reducer that reduces output rotation of an electric motordisposed on the shaft center and a differential gear device thatdistributes the output rotation of the speed reducer to a pair of leftand right axles, wherein the first power transmission member is any oneof a plurality of rotating elements of the speed reducer, and whereinthe second power transmission member is an input shaft of the speedreducer disposed on an output shaft of the electric motor in arelatively non-rotatable manner.
 6. The vehicle power transmissiondevice of claim 3, comprising a speed reducer that reduces outputrotation of an electric motor disposed on the shaft center and adifferential gear device that distributes the output rotation of thespeed reducer to a pair of left and right axles, wherein the first powertransmission member is any one of a plurality of rotating elements ofthe speed reducer, and wherein the second power transmission member isan input shaft of the speed reducer disposed on an output shaft of theelectric motor in a relatively non-rotatable manner.
 7. The vehiclepower transmission device of claim 1, wherein the gear portion is aparking lock gear.
 8. The vehicle power transmission device of claim 2,wherein the gear portion is a parking lock gear.
 9. The vehicle powertransmission device of claim 3, wherein the gear portion is a parkinglock gear.
 10. The vehicle power transmission device of claim 4, whereinthe gear portion is a parking lock gear.
 11. The vehicle powertransmission device of claim 5, wherein the gear portion is a parkinglock gear.
 12. The vehicle power transmission device of claim 6, whereinthe gear portion is a parking lock gear.
 13. The vehicle powertransmission device of claim 1, wherein the second power transmissionmember is rotatably supported via the second bearing and a third bearingon the both sides of the gear portion in the shaft center direction. 14.The vehicle power transmission device of claim 2, wherein the secondpower transmission member is rotatably supported via the second bearingand a third bearing on the both sides of the gear portion in the shaftcenter direction.
 15. The vehicle power transmission device of claim 3,wherein the second power transmission member is rotatably supported viathe second bearing and a third bearing on the both sides of the gearportion in the shaft center direction.
 16. The vehicle powertransmission device of claim 4, wherein the second power transmissionmember is rotatably supported via the second bearing and a third bearingon the both sides of the gear portion in the shaft center direction. 17.The vehicle power transmission device of claim 5, wherein the secondpower transmission member is rotatably supported via the second bearingand a third bearing on the both sides of the gear portion in the shaftcenter direction.
 18. The vehicle power transmission device of claim 6,wherein the second power transmission member is rotatably supported viathe second bearing and a third bearing on the both sides of the gearportion in the shaft center direction.
 19. The vehicle powertransmission device of claim 7, wherein the second power transmissionmember is rotatably supported via the second bearing and a third bearingon the both sides of the gear portion in the shaft center direction. 20.The vehicle power transmission device of claim 8, wherein the secondpower transmission member is rotatably supported via the second bearingand a third bearing on the both sides of the gear portion in the shaftcenter direction.